Cluster AgeS Experiment (CASE): Dwarf Novae and a Probable Microlensing Event in the Globular Cluster M22
Pietrukowicz, P.; Thompson, I. B.; Schwarzenberg-Czerny, A.; Kaluzny, J.; Krzeminski, W.; Pych, W.; Jaroszynski, M.
Abstract
We report the identification of a new cataclysmic variable (denoted as CV2) and a probable microlensing event in the field of the globular cluster M22. Two outbursts were observed for CV2. During one of them superhumps with P_sh=0.0887 d were present in the light curve. CV2 has an X-ray counterpart detected by XMM-Newton. A very likely microlensing event at a radius of 2.3 arcmin from the cluster center was detected. It had an amplitude of Delta V=0.75 mag and a characteristic time of 15.9 days. Based on model considerations we show that the most likely configuration has the source in the Galactic bulge with the lens in the cluster. Two outbursts were observed for the already known dwarf nova CV1.